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F-GEO-Naturvitenskap, geofag

Search for reliable signals of catastrophic failure

Tildelt: kr 0,72 mill.

A sudden catastrophic failure causes enormous damage in terms of properties and lives. However a reliable precursor of such failures can save a lot, by allowing evacuation and other precautionary measures. From this motivation, the main goal of our projec t is to identify reliable precursors of catastrophic failures in breakdown situations. In some failure models (fiber bundle model, fuse model) we observe that the avalanche distribution shows a crossover behavior near the breakdown point. A recent observ ation suggests such crossover behavior exists in magnitude distribution of earthquakes in Japan, which encourages the possibility of using the crossover signature as a reliable precursor of catastrophic failure. We want to verify the crossover signatur e in different situations of failure. First, we want to analyse the avalanches in material failures, which are available as acoustic emissions. Next we want to deal with the earthquake data of a tectonically active region. Our next goal is to analyse the Mode II fracture scenario in fault zones, which plays crucial role in stress development and release during earthquakes. As the fractured surfaces are self affine, we plan to study the variation of contact areas between two overlapping self-affine asperi ties, which may explain the observed spatial stress distributions before a big earthquake. We want to explore the role of friction in the stick-slip dynamics of two overlapping surfaces. The stick-slip models incorporate the effect of frictions and the ou tcome is a series of small avalanches before the global failure. Does the avalanche distribution show crossover behavior near global failure? By analysing the avalanche time series in fiber bundle model, we observe a characteristic variation of response parameters which may be considered as a precursor. Can we explain the observation analytically? Can we get similar signature in more complex systems, like fuse model?

Budsjettformål:

F-GEO-Naturvitenskap, geofag

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